Conventionally, inspecting and treating a lesion area (for example, constricted area) within a biological organ by introducing a catheter into the biological organ such as a blood vessel or the like has been widely performed. In general, this kind of catheter has an elongated shaft constituting a catheter main body and a hub which is connected to a proximal portion of the shaft (for example, refer to U.S. Pat. No. 6,355,027 and JP-A-9-637).
In use of such a catheter, it may be necessary to selectively advance the shaft into blood vessels which are complicatedly branched in a living body or lumens in a living body in order to make a distal end of the catheter reach a target area in a living body. For this reason, in general, a guide wire is inserted through a lumen of a catheter, which is then run through a blood vessel or a lumen in a living body along the guide wire in a state where a distal end of the guide wire is made to precede the distal end of the catheter.
However, in some cases, the guide wire is used by bending (angling) one or more portions, for example, a plurality of a distal portion of the guide wire in advance in order to select a blood vessel or control the direction of the distal end of the catheter. When inserting the guide wire of which a distal portion is angled in this manner into the catheter from a proximal opening portion of a hub of the catheter, the most distal portion of the guide wire can come into contact with a part of an inner peripheral surface of the hub and the guide wire can advance to the hub while the other end of the guide wire can come into contact with an inner peripheral surface of the hub on a side opposite to the contact area. In this case, a luer taper in which the inner diameter is reduced at a constant ratio toward a distal direction can be provided in the conventional hub. Therefore, the inner diameter of the hub becomes smaller toward a distal side and the frictional resistance between the guide wire and the inner peripheral surface of the hub becomes greater along with the reduction of the inner diameter. For this reason, the movement of the guide wire can be inhibited on the inner peripheral surface of the hub, and therefore, in some cases, it can be difficult to further move the guide wire to the distal side.